Radiation cured island coating system

ABSTRACT

A process for manufacturing a metallized substrate using the island coating method, includes depositing a coating layer containing a radiation curable non-volatile film former. The coated part is then vacuum metallized to form the metal islands of the present invention. A layer of clear resinous protective dielectric topcoat containing a radiation curable non-volatile film former is then deposited to completely cover the layer of metal islands while maintaining the aesthetic properties of the metallizing island coating system at a reduced cost and with minimal variability among parts.

This application is a continuation of application(s) Ser. No. 08/426,101filed on Apr. 21, 1995, now abandoned, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

This invention pertains to vacuum deposition of amphoteric materials.

BACKGROUND OF THE INVENTION

Vacuum metallizing of plastic and similar dielectric substrates isdisclosed in various forms including U.S. Patents:

    ______________________________________                                        2,992,125            Fustier                                                  2,993,806            Fisher                                                   3,118,781            Downing                                                  3,914,472            Nakanishi                                                4,101,698            Dunning                                                  4,131,530            B1um                                                     4,211,822            Kurfman                                                  4,215,170            Oliva                                                    ______________________________________                                    

In addition, two reference books are:

Thin Film Phenomena, Kasturi L. Chopra, Robert E. Kreiger PublishingCompany, Huntington, N.Y., 1979. pp. 163-189.

Handbook of Thin Film Technology, Leon I. Maissel and Reinhard Glang,McGraw-Hill Book Company, New York, N.Y., 1970., pp. 8-32 to 8-43.

U.S. Pat. Nos. 4,407,871, 4,431,711 and 4,713,143, assigned to assigneeof the present invention and incorporated herein by reference, relate tometallizing of plastic articles and more particularly to the structureand spacing of discrete metal islands used to metallize rather than acontinuous metal film. The metallizing is performed utilizing the islandcoating system as detailed in the aforesaid patents. The system includesgenerally spray depositing sequentially a primer coating layer, abasecoat coating layer, a metallizing layer and a topcoat layer. Asdisclosed in the above referenced patents, the coating layers containnon-volatile film forming polymers, generally in the range of 10-30%requiring flash time of 20 minutes at ambient temperature and cure timesof approximately 30 minutes at 260° F. between application of layers.

In addition to proper deposition of the coating layers, the appearanceand performance of the commercial product, the conductivity of the metallayer, the corrosion resistance of the metal layer and/or the adhesionof the top coat all relate to the structure and spacing of the islands.The above referenced patents provide further teachings related tonucleation and film growth to the desired island structure and spacingthat achieves these ends.

In U.S. Pat. No. 5,290,625, assigned to the assignee of the presentinvention and incorporated herein by reference, the above process isapplied to aluminum parts. In a copending application, U.S. Ser. No.08/248,957, assigned to the assignee of the present invention andincorporated herein by reference, the coating layers are modified toform a combined primer/basecoat layer. The underlying combinedprimer/basecoat can include a pigment to provide a colored metallicappearance as disclosed in U.S. Pat. No. 5,320,869 issued Jun. 14, 1994and assigned to assignee of the present invention and incorporatedherein by reference. In another copending application, U.S. Ser. No.08/248,649, assigned to the assignee of the present invention andincorporated herein by reference, the technology for coating layerdeposition is improved to allow film builds of 1.5 to 2.0 mils,eliminating significant coating irregularities.

The current island coating system spray deposits the polymericconstituents of the primer layer, basecoat layer and topcoat layer inorganic solvent carriers such as glycol ethers, glycolether acetates,aromatic hydrocarbons and dibasic esters. These solvent carriers pose awaste disposal problem increasing the cost of production significantly,a flammability hazard, as well as requiring significant flash and curetimes. If the organic solvents could be eliminated, while stillmaintaining the aesthetic properties of the metallized appearance,significant savings in time and therefore increased production, improvedsafety, as well as ease of waste disposal would be attained.Additionally, with the elimination of organic solvents the range ofsubstrates that can be metallized could be increased.

In general, the step of spray depositing is done for batch processingwhile the parts are being rotated as described in U.S. Pat. No.5,284,679 issued Feb. 8, 1994 and assigned to the assignee of thepresent invention, and incorporated herein by reference. However, theuse of rotation is not practical when dealing with substrates that arethin sheets such as thin extruded polymers, cellulose based materialsand textiles. These thin gauge sheets or sheetstocks require differenthandling and for high speed production it would be useful to be able tohave continuous in-line processing.

Apparel designers would find it advantageous to have a metallizedsheetstock made from various materials such as polymers, vinyls,cellulose based materials and textiles, that are flexible, washable,formable, and die cutable. Currently available metallic trims aregenerally either not truly metallic in appearance, or upon washing andwetting lose metallic luster or cannot be washed at all. Further, itwould be advantageous to have materials with a metallized appearancethat can be "ironed on", i.e. a thermal bonding adhesive, in addition to"stitched on". As one example, athletic shoe manufacturers have aperceived need to individualize their products with unique, identifiablefeatures, as for example lights that are present on one brand ofathletic shoes. Metallic trim would be useful in creating suchidentifiable features.

It would be useful to have thin polymer extrusion metallic finishproducts that can be cut on high speed electrically resisted die bladeswithout arcing. Further it would be useful to be able to utilize suchmaterials as exterior trim without corrosion and which can be used forin-mold decorating and which have the proper reflectivity or depth ofimage.

SUMMARY OF THE INVENTION AND ADVANTAGES

According to the present invention, a process for manufacturing ametallized substrate using the island coating system, includesdepositing a first coating layer containing a radiation curablenon-volatile film former. The coated substrate is then vacuum metallizedto form the metal islands of the present invention and a layer of clearresinous protective dielectric topcoat containing a radiation curablenon-volatile film former is deposited to completely cover the layer ofmetal islands while maintaining the aesthetic properties of themetallizing island coating system at a reduced cost and with minimalvariability.

The substrate can be formed parts of various polymers or metals or thesubstrate can be a sheetstock made from materials such as a thin gaugeextruded polymer, vinyl, textile or cellulose based material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention provides a process of manufacturingsubstrates/parts, and the manufactured parts/substrates themselves, thathave a metallized appearance, that reduces the amount of organic wastesand production time as well as allowing continuous in-line processing ofsheetstock utilizing the island coating system.

The part can be made from a substrate material selected from the groupcomprising crystalline and/or amorphous thermoplastic elastomers such asthermoplastic urethanes, thermoplastic urethane alloys, polyesteralloys, thermoplastic olefins, polyamide alloys and metals such asaluminum, magnesium and steel.

Further the substrate material can be in a thin gauge sheet form, i.e.sheetstock. The sheetstock has a thickness range of from 0.002 inches to2 inches with 0.002 to 0.5 inches being the preferred range. Thesheetstock can also include textiles such as, but not limited to,cotton, denim, canvas as well as vinyls and cellulose based materialsincluding rayon.

In-line processing refers to a process wherein the material beingtreated is moved from one holding means and taken up by another andwhile moving between is treated by the process. For example,reel-to-reel processing would be one means of in-line processing.

The island coating system is then applied as taught in U.S. Pat. Nos.4,407,871, 4,431,711, 4,713,143, 5,290,625 with the improvementsdisclosed in the present invention. The island coating system includesgenerally as a first coating layer either a combined primer/basecoatlayer, or separately applied primer and basecoat layers, a metallizinglayer and an encapsulating topcoat layer. The prior art teaches thateach coating layer contains film forming polymers as disclosed in theabove referenced patents and patent applications.

The coatings of the present invention contain oligomers which can beclassified as film forming polymers or resins in standard coatingtechnology. The oligomers are blended with monomers which are lowviscosity and are considered reactive diluents providing viscosityreduction to the coating and they react with oligomers when exposed toUV light. A photoinitiator is also required.

Two publications which provide general background information onradiation curing are:

Cationic Radiation Curing, J. Koleske, Federation Series on CoatingsTechnology, Federation of Societies for Coating Technology, June, 1991;and

Radiation Cured Coatings, J. Costanza et al., Federation Series onCoatings Technology, Federation of Societies for Coating Technology,June, 1986.

In the coatings of present invention, the film forming polymers areradiation curable film formers. The radiation curable non-volatile filmformer is selected from the group consisting of melamine acrylate,urethane acrylate, epoxy acrylate, acrylic acrylate and polyesteracrylate.

With the utilization of radiation curable film formers, no organicsolvents are required in the present invention. Flammability hazards areeliminated as well as wastes. The present invention provides for theexposure to the radiation to occur outside the coating room, thereforethe excess coating fluid can be collected and recycled for reuse.

The formulation of each coating layer is therefore:

Primer:

0-5% pigment

30-90% radiation curable film former

1-5% photoinitiator

2-70% monomers

Basecoat:

30-90% radiation curable film former

1-5% photoinitiator

2-70% monomers

Combined primer/basecoat:

0-5% pigment

30-90% radiation curable film former

1-5% photoinitiator

2-70% monomers

Topcoat:

0-3% UV absorber

30-90% radiation curable film former

1-5% photoinitiator

2-70% monomers

The photoinitiator is selected from the group consisting ofphenylketones, benzophenone, diazonium salts, diaryliodonium salts,triarylsulphonium salts, benzoin ethers, thioxantones and oxime esters.

The pigment can be black or other colors such as red, green, yellow orpurple. In the preferred embodiment a black pigment is used.

In the practice of the improvements of the present invention, theprimer, basecoat and topcoat layers (or coatings) can be appliedutilizing spray technology, generally high volume, low pressure sprayequipment to atomize the coatings. The coatings may be heated (100°-120°F.) to assist with coating flow out. The coatings are applied while theparts are at ambient or elevated temperature (20°-150° F.). If preformedparts are being coated, the parts can be done in "batch" and in thepreferred embodiment while the parts are rotating.

If the substrate is a sheetstock, in-line processing can be used forhigh volume processing utilizing the present invention. For this processcoatings can be applied with spray technology but also roller or knifedeposition as is known in the art can be used. D. Satas, Web Processing& Converting Technology & Equipment, VanNostrand, Reinhold, N.Y., 1984;Kallendorf, C. F., ed. Radiation Curing Primer I: Inks, Coatings &Adhesives, Rad Tech International Park America, 60 revere Drive, Suite500, Northbrook, Ill. 60062, 1990. For low volume applicationsindividual sheets can be processed using either current metallizationprocedures or the present invention.

Generally only one side of the sheetstock is metallized, but both sidescan be metallized. The one side metallized can be on the first surface,e.g., the surface of the substrate that faces in the direction of thelight impinging on the substrate carrying the discontinuous layer ofmetal. In this case the light impinging on the surface of the substratepasses through the discontinuous layer of metal first with part of thelight being reflected back from the metal islands and not reaching thesurface.

Alternatively the metallizing can be on the substrate surface oppositethe first surface. In this case the opposite surface, or second surface,has the discontinuous layer of metal formed thereon and the light passesthrough the substrate (either transparent or translucent material)before it is reflected back through the substrate again from thediscontinuous layer of metal.

The coatings in the present invention do not require a flash time sincethere are no solvents to evaporate. The coatings are cured byultraviolet radiation from a suitable source such as an ultraviolet lampfor less than five minutes. The coating thicknesses are between 0.5 and2.0 mils for each coating as set forth in the prior art with 1.5 milbeing the preferred thickness.

Because of the elimination of the flash step and the significantreduction in cure time compared to the prior art island coating system,the time to produce metallized parts is reduced. The efficiency of theproduction line making metallized parts is increased by at least 60% andcontinuous in-line processing of sheetstock can be undertaken.

In a second embodiment, liquid inorganic carriers such as CO₂ can besubstituted for part of the organic solvent carriers as marketed byUnion Carbide in their UNICARB® system. Applicant has utilized thissystem and in the practice of the present invention some organicsolvents are necessary to maintain proper flow rate and consistency.

In a further embodiment, a hardcoat layer is applied on the topcoatlayer. The hardcoat layer can be applied to improve scratch resistance.This hardcoat layer can be applied to improve scratch resistance whereflexibility is not required. This hardcoat layer can be selected fromthe group consisting thermally cured silicone coatings and UV curedacrylate and methacrylate coatings.

The present invention provides thin extrusion polymer sheetstock with ametallic finish. These thin extrusion polymers have wide application inexterior and interior trims, particularly in the automotive industry. Inthe prior art sheetstock with a continuous, non-island, metallized layerwhen cut on high speed electrically resisted die blades would arc.However, metallized sheetstock prepared with the island coating systemcan be die cut since no arcing can occur because the metal layer is notconductive. In general for these applications, the sheetstock isselected from crystalline and/or amorphous thermoplastic elastomers suchas thermoplastic urethanes, thermoplastic urethane alloys, polyesteralloys, thermoplastic olefins, polyamide alloys as well as vinyls,textiles and cellulose based materials.

The present invention provides metallized thin extruded elastomericplastic sheets, 0.002 to 0.010 inches in thickness, which can be usedeffectively in trim applications without crinkle. Because of theflexible nature of the island coating these sheets can be stretched overcomplex geometric shapes as well as be "molded in" to complex shapedproducts to eliminate the need for an adhesive. In second surfaceapplications, depth of image (DOI) provides an exact image as doeschrome without the performance problems of chrome.

The present invention also provides a metallized substrate which isflexible, washable, and can be either attached with adhesive or stitchedto an appropriate object and in particular to wearing apparel. Themetallization can be performed either as taught by U.S. Pat. Nos.4,407,871, 4,431,711 and 4,713,143, or with the improvements of thepresent invention. The object can be clothes, shoes or the like.

These improvements allow the substrate to be materials which should notbe exposed to organic solvents such as textiles and continuous in-lineprocessing, i.e. metallizing, can be used to manufacture the substrate.The substrate for use in apparel and trims is generally selected fromthe group consisting of polymers, generally a thermoplastic urethane(TPU), vinyls, cellulose derived materials such as paper, wood andrayon, and textiles such as cotton, wool and silk. The substrate can bein any shape, but in the preferred embodiment it is in sheet form sothat it can be die cut into the appropriate shape to be applied toapparel. Further, in another preferred embodiment the substrate can belaundered using standard procedures and can go through the drying cycleof a dryer. Polyester elastomer substrates such as HytrelI andpolyurethane elastomer substrates such as RyniteI have been used in thepresent invention as well as thermoplastic polyester sheetstock such asEstaneI. The substrate can be formed into trims for apparel or appareltrim itself can be processed with the present invention. Furtherarticles of clothing themselves, such as shoes, can also be metallizedwith the present invention.

Additional appearance modifications can be achieved by eithermechanically abrading the metal layer in random or structured patternsprior to topcoating. "Splattering" the metal layer with 1% nitric,sulfuric or hydrochloric acid prior to topcoating also provides amottled visual effect.

The present invention also provides the advantages that differentpigments can be added to the basecoats or dyes added to the topcoat toproduce different colored appearances. Alternatively, the substrateitself can have color as set forth in the '869 Patent. Also, secondaryaccents can be achieved by painting directly over the topcoat.Additionally, ink transfers in a variety of patterns can also be appliedin order to produce a variety of looks, as for example snakeskin andgeometric patterns.

The process provides metallized sheetstock which can be formed into trimwhich are metallic in appearance and are flexible, washable and formableinto sheets for die cutting. The process also provides for theapplication of the island coating system on both cellulose derived andtextile materials.

The invention will now be described by way of the following exampleswith it being understood that other advantages and a more completeunderstanding of the invention will be apparent to those skilled in theart from the detailed description of the invention.

EXAMPLE 1

Four preformed parts for automobiles were metallized utilizing theisland coating system as in the present invention. The radiation curablecombination primer/basecoat was spray coated and then cured by a 1minute exposure to a UV lamp. The parts were rotated during theexposure. The parts were then vacuum metallized with indium and aradiation curable clear topcoat was then spray coated onto the part.Curing was by a 1 minute exposure to a UV lamp. The parts were rotatedduring the exposure.

    ______________________________________                                        Part         Material      Appearance                                         ______________________________________                                        Headlight    Acrylonitrile Bright, smooth                                     Reflector    butadiene styrene                                                                           reflective                                         Doorpull     Glass filled Nylon                                                                          Bright, smooth                                                                reflective                                         Wheel        Aluminum      Bright, smooth                                                                reflective                                         Radiator     Thermoplastic Bright, smooth                                     Grille       Urethane      reflective                                         ______________________________________                                    

The parts all had a metallized appearance that was within acceptableparameters. Diffuse reflectance was within 45-65 units, distinctness ofimage (DOI) was >90 units, gloss was >100 units and haze was <23 unitsfor each part.

EXAMPLE 2

Two molded footwear heel plates and two pieces of TPU sheetstock weremetallized. The samples were washed in a home washing machine and driedin a home dryer through ten cycles over a period of several days.Generally the washing cycles included a warm wash and a cold rinse witha commercial laundry detergent and non-chlorine bleach. The dryer wasset on an automatic cycle which is approximately 35-40 minutes.

The samples were then evaluated and found to have no loss offlexibility, no change in color and no coating delamination.

Throughout this application various publications are referenced bycitation or patent number. The disclosures of these publications intheir entireties are hereby incorporated by reference into thisapplication in order to more fully describe the state of the art towhich this invention pertains.

The invention has been described in an illustrative manner, and it is tobe understood that the terminology which has been used is intended to bein the nature of words of description rather than of limitation.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is, therefore, to beunderstood that within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

What is claimed is:
 1. A process for manufacturing a metallizedsubstrate comprising the steps of:providing a substrate; depositing afirst coating layer containing a radiation curable non-volatile filmformer; vacuum depositing a layer of metal material to form adiscontinuous film covering the first coating layer including aplurality of discrete islands of a metal material appearingmacroscopically as a continuous film of such metal and having aplurality of macroscopically unobservable channels between the islandsto maintain the film electrically non-conductive over the first coatinglayer; and depositing a layer of clear resinous protective dielectrictopcoat containing a radiation curable non-volatile film former tocompletely cover the layer of vacuum deposited corrosive metal materialand filling the channels for bonding the metal material to the firstcoating layer throughout the bottom of the channels.
 2. The process formanufacturing a metallized substrate as set forth in claim 1 wherein thefirst coating layer is one of a combined primer/basecoat layer andseparately applied primer and basecoat layers.
 3. The process formanufacturing a metallized substrate as set forth in claim 2 wherein theprimer, basecoat, combined primer/basecoat and topcoat layer have athickness in the range of 0.5 mil to 2.5 mils and each layer can havethe same or different thickness.
 4. The process for manufacturing ametallized substrate as set forth in claim 3 wherein the topcoat layerhas a thickness of 2.0 mils.
 5. The process for manufacturing ametallized substrate as set forth in claim 1 wherein the radiationcurable non-volatile film former is selected from the group consistingof melamine acrylate, urethane acrylate, epoxy acrylate and polyesteracrylate.
 6. The process for manufacturing a metallized part as setforth in claim 1 wherein the substrate is made from a material selectedfrom the group consisting of crystalline and amorphous thermoplasticelastomers, polyester alloys, thermoplastic olefins, polyamide alloysand metals.
 7. The process for manufacturing a metallized substrate asset forth in claim 1 wherein the substrate is a sheetstock, with athickness from 0.002 to 2.0 inches, selected from the group consistingof crystalline and amorphous thermoplastic elastomers, polyester alloys,thermoplastic olefins, polyamide alloys, metals, polyester elastomers,polyurethane elastomers thermoplastic polyesters, vinyls, textiles andcellulose based materials.
 8. The process of claim 7 furthercharacterized by the step of abrading the metal layer in random orstructured patterns prior to topcoating.
 9. The process of claim 7further characterized by the step of splattering the metal layer with anacid selected from the group consisting of 1% nitric, sulfuric andhydrochloric acid prior to topcoating wherein a mottled effect visualeffect is provided.
 10. The process of claim 1 wherein the exposure tothe radiation occurs spaced from the depositing of the coating layer,whereby the excess coating layer can be collected and recycled forreuse.
 11. The process of claim 1 wherein a photoinitiator is added tothe radiation curable non-volatile film former.
 12. The process of claim11 wherein the photoinitiator is selected from the group consisting ofphenylketones, benzophenone, diazonium salts, diaryliodonium salts,triarylsulphonium salts, benzoin ethers, thioxantones and oxime esters.13. A process for manufacturing a metallized trim for apparel comprisingthe steps of:providing a substrate suitable for apparel trim; depositinga first coating layer containing a radiation curable non-volatile filmformer on the substrate; vacuum depositing a layer of metal material toform a discontinuous film covering the first coating layer including aplurality of discrete islands of a metal material appearingmacroscopically as a continuous film of such metal and having aplurality of macroscopically unobservable channels between the islandsto maintain the film electrically non-conductive over the first coatinglayer; and depositing a layer of clear resinous protective dielectrictopcoat containing a radiation curable non-volatile film former tocompletely cover the layer of vacuum deposited corrosive metal materialand filling the channels for bonding the metal material to the firstcoating layer throughout the bottom of the channels.
 14. The process formanufacturing a metallized trim for apparel as set forth in claim 13wherein the first coating layer is one of a combined primer/basecoatlayer and separately applied primer and basecoat layers.
 15. The processfor manufacturing a metallized trim for apparel as set forth in claim 13wherein the substrate is made from a sheetstock selected from the groupconsisting of crystalline and amorphous thermoplastic elastomers,polyester alloys, thermoplastic olefins, polyamide alloys, metals,polyester elastomers, polyurethane elastomers thermoplastic polyesters,vinyls, textiles and cellulose based materials.
 16. The process of claim13 further characterized by the step of abrading the metal layer inrandom or structured patterns prior to topcoating.
 17. The process ofclaim 13 further characterized by the step of splattering the metallayer with an acid selected from the group consisting of 1% nitric,sulfuric and hydrochloric acid prior to topcoating wherein a mottledeffect visual effect is provided.
 18. The process of claim 13 wherein aphotoinitiator is added to the radiation curable non-volatile filmformer.